The present invention relates to rotary connection means acting by frictional engagement (also termed frictional revolving joint), such means having                a hollow shaft to be slip-on attached onto a shaft, and a tapered ring arrangement, including a least one tapered ring section having an inner surface for close positioning in relation to the hollow shaft, and an oblique outer surface;        at least one tensioning ring element having an oblique inner surface, which slides between a starting position and a tensioning or clamping position on the oblique outer surface of the tapered ring section; and        tensioning means for moving the tensioning ring element into the tensioning position.        
From DE 25 14 313 A1 a rotary connector acting by frictional engagement of the afore-mentioned type is known as a detachable shaft/hub-connection for interconnecting two shaft ends. The hollow shaft is designed as a ring comprising two shaft ends to be interconnected, on which ring there are arranged two pressure rings with oblique outer surfaces and two tensioning washers having an oblique inner surface, which, respectively, correspond to the afore-mentioned tensioning ring element, as well as a tensioning device serving as tensioning means and being comprised of tensioning bolts or screws and of sliding or link blocks being adjustable thereon. In order to interconnect the two shaft ends the tensioning bolts and the shaft/hub-connection are tightened. Consequently the link blocks slide outwardly on the tensioning bolts and, via the tensioning washers and the pressure rings, exert radial forces onto the ring and the shaft ends to be connected with the ring. The link blocks spread apart the tensioning washers in an axial direction starting from a starting position until the tensioning position has been reached, in which the shaft/hub-connector is firmly connected to the two shaft ends.
The link blocks in context with the tensioning bolts, are provided for retaining the tensioning washers in the tensioning position, with the link blocks preventing sliding back of the two tensioning washers from the tensioning position into the starting position. The link blocks and the tensioning bolts consequently form the tensioning means with which the tensioning washers are brought into the tensioning position to be held there in and thus to be retained.
It largely depends on the skill of the personal staff tightening the tensioning bolts whether or not the tensioning washers create sufficient radial forces for safe connection by frictional engagement between the ring and the two shaft ends. Attention has to be paid to the link blocks each transmitting adequately even forces onto the tensioning washers, respectively, in order to load the tensioning washers evenly over their inner circumferences. Due to the oblique contacting surfaces of the link blocks and the tensioning washers, upon tightening thereof, their biasing forces will permanently act in the direction of the starting position onto the link blocks as well as onto the tensioning bolts. Thus the biasing forces counteract the retention function of the tensioning washers in the tensioning position.
Rotary connection means based on load transmission produced by friction, of the type mentioned in the introductory portion of this description are also known from prior art by way of U.S. Pat. No. 5,947,626 for connecting a shaft with a hollow shaft. The device shown therein comprises a tapered ring arrangement to be pushed onto the hollow shaft. This arrangement includes two tapered ring sections and has oblique outer surfaces which decline toward the centre when seen in the cross section of the tapered ring arrangement. There are two tensioning ring elements arranged on the oblique outer surfaces of the tapered ring arrangement and having oblique inner surfaces adapted correspondingly to the oblique outer surfaces of the tapered ring arrangement. Thereby, the tensioning ring elements are capable of sliding on the tapered ring arrangement. By applying hydraulic pressure onto a hydraulic port formed in a tensioning ring a pressure ring chamber is created between the tensioning ring elements. On its outer side, the pressure ring chamber is restricted by a ring collar of a tensioning ring element. On its inner side the pressure ring chamber is restricted by an intermediate ring element. At the ring collar and the intermediate ring element the pressure ring chamber is sealed by annular sealing means in each position of the tensioning ring elements.
By applying hydraulic pressure to the pressure ring chamber the tensioning ring elements are spaced apart and made to reach a tensioning position in which the tensioning ring elements exert pressure via the inclined surfaces of the tapered ring arrangement onto the hollow shaft thus to create rotary connection by frictional engagement between the hollow shaft and the shaft.
In order not to have to maintain hydraulic pressure permanently during operation there is provided mechanical securing or retention of the tensioning ring elements in their tensioning position. To this end, fastening bolts or screws are arranged laterally along the circumference of the tensioning ring elements.
A further type of rotary connection by frictional engagement is disclosed by DE 43 32 477. In contrast to the device mentioned in the introductory portion this apparatus shows a stationary bearing ring besides two tensioning ring elements. In this case a pressure ring chamber is formed between the bearing ring and the tensioning ring element arranged at the side thereof.
The known devices are essentially disadvantageous in that the assembly thereof is very complex, because, for securing the tensioning ring elements in the tensioning position, tightening of the fastening bolts becomes necessary. On the other hand, for releasing the friction-engagement connection the fastening screws have to be loosened in first place. A further disadvantage is that due to the maximum stability and the maximum number of bolts along the circumference of the tensioning ring elements maximum load transmission is predetermined. Thus the torque of the rotary connection to be transmitted at the maximum is predetermined. Particularly, in the case of applying a rotary connection of frictional engagement in modern wind energy plants, the maximum torque of the connection presently to be achieved does not suffice.